I am on the last lap of my catch up work but I am finding it increasingly difficult to work and I do not know why. This is giving me a blardy headache! When I say difficult, it means that I am having problems with my computer. My browser keeps freezing and I am unable to do anything until it rights itself, or it get shuts down altogether and had to be reopened. 

I want to upgrade my Firefox browser to the latest but I am afraid that I would not be able to downgrade to a previous version if it doesn't perform as I expected it to. In fact, I read some horrible reviews of the browser being extremely slow! What's happening? I don't want to change to Chrome. Don't like it either!